Structural unit



Jan. 19, 1943. H. 1... MITCHELL STRUCTURAL UNIT Filed Aug. 15, 1940 ATTORNEYS Patented Jan. 19, 1943 STRUCTURAL UNIT Holger L. Mitchell, Milwaukee, Wis., asslgnor to Koehrlng Company, Milwaukee, Wis., a corporation Application August 15,1940, Serial No. 352,789

9 Claims. (on. 29-455) This invention comprises a novel structural unit and method of making the same, particularly useful for the building of booms, beams, girders, and like structural elements useful for many diflerent purposes in the arts.

A primary object of the invention has been to devise a novel structural unit of the type mentioned, combining ina new way tube and angle bar shapes peculiarly welded together to afiord a high degree of strength and rigidity in their final assembled condition.

Another object of the invention has been to devise a method of cutting or shearing the tubular elements of the unit and at the same time forming them with welded edges of enlarged area to ailord a maximum; extent of welded connection when the tubular elements are assembled and secured to the angle plateor bar members after the teachings of the invention, all conducive to the production of the desired strength in the making of lattice type structural units of the class improved upon, I

Included within the invention is a novel form of splicing means for sections of structural units built in accordance with the invention.

The accompanying drawing shows a preferred embodiment of my invention as incorporated in a boom or beam of oblong cross section, but it is to be understood that I do not limit myself to this special type of structural unit because the structure and principle of assemblage of parts oi my invention may be used to advantage'in respect to the design of flat girders, round columns, U-beams, angle beams, or the like.

In the accompanying drawing:

Figure 1 is a fragmentary side view showin in elevation a structural unit made in accordance with my invention.

Figure 2 is a fragmentary view in elevation showing .in somewhat enlarged illustration the mode of assembling the tubular member and the angle plate or bar member of the unit.

Figure 3 is a sectional view taken about on the line '8-3 of Figure 2 and bringing out more clearly the welded connection between the tubular element and the angle bar member.

Figure 4 is a cross sectionalview through the structural unit taken about on the line of Figure 1, looking in the direction of the arrow and illustrating the arrangement of parts at the splicing Joint.

Figure 5 is a fragmentary detail view taken on the line 55 of Figure 4, illustrating more fully the bolted disc parts at the splice joint;

Describing my invention specifically, I illustrate in Figure 1 a boom or beam section of the lattice type wherein, as best seen in Figure 4, the structural unit is made up in an oblong cross section, substantially speaking, utilizing four an-- gle bars l at the corners, which angle bars are connected by means of tubular members 2 arranged at angles to the longitudinal axis of the unit in the manner of the formation of customary angular struts employed in the building of units of this type.

In practicing the method of assembling the parts I and 2 according to the invention, it is contemplated to subject the ends of tubular members 2 to the cutting action of any suitable type of shearing machine, and by so doing the end portions of the members 2 are compressed into a tapered shape as shown at is and are cut or sheared at about a 45 angle to provide the contour illustrated in side view in Figure 2 and in longitudinal edge view in Figure 3. The compressing-of the tubular section oi the member 2 by the shearing action of the cutting machine flattens the ends of the member 2 and thereby elongates said members to an extent considerably greater in longitudinal dimension, at the edgefthan the tubular cross section of the tube at its main body portion. Likewise, the ends of the tubular member 2 are sheared at diagonal angle so as to provide the edge 3, as seen in Figure 3 particularly, and it is contemplated that the angle bars or plates lshall be formed with bevel edges 1 leading from the inner sides of said parts, see Figure 3. I Then the edge of each tubular member 2 at its end is joined with the peak of the bevel edge e of the adjacent portion of the angle bar I at the point 5, see Figure 3, and thus the parts I and 2 are so assembled as to provide a space for receiving the welding material by which the welded joint 6 is provided.

The joint 6 tapers toward the point of contact or connection 5 between the parts i and 2, as will be seen in Figure 3, and affords a very eiiective and rigid connection according to welding practice, as will be readily apparent.

The outer side of the tubular element or member 2 is, by reason of thefmode of shearing or flattening the ends thereof, and welding it to the members I, disposed almost in the plane of the outer sides of said members I. In forming a structural unit as seen in Figure 1, the tubular elements 2 at one side of the beam, boom, or girder, whatever the structural unit may be, will be angularly disposed in an opposite direction to those at the opposite side, after the customary practice of building lattice units of this type, all with a view to maximum rigidity and strength.

As a convenient mode of connecting sections of units of the type illustrated in Figure 1, it is contemplated to weld or otherwise attach to each longitudinal angle bar I at its splicing ends a disc I, and the discs of adjacent splicing ends of such bars will be disposed in flat face contacts and connected by bolts or rivets, bolts 8 being illustrated. Crossed or diagonal angle bars 9 are bolted to the discs, said members 9 being welded or otherwise attached as shown at It! at their crossed middle portions and providing diagonal braces for the efiective connection of the various members I of the assembled unit. The bolts or members connecting the parts 9 or i are designated ii and this arrangement will be self-evident from the foregoing description.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A structural unit of the class described, comprising a tubular member sheared at an end portion thereof to flatten or taper such end portion to a dimension larger than the general cross section of the tubular member, and a bar having an edge portion thereof welded to the sheared edge of said tubular member.

2. A structural unit of the class described, comprising a lattice type beam made up of spaced plates and tubular members therebetween, the tubular member being arranged to provide with the plates a lattice type structure in which the tubular members are disposed at an angle to the axis of the plates, said tubular members being sheared at approximately a .45 angle at their ends to flatten the same at their end edges to a dimension greater than the cross sectional diameter of such members, and weld joints connecting the plates and the sheared end edges of the tubular members.

3. The process of making a beam, girder, boom, or the like as a structural unit, which comprises shearing a tubular member at an end thereof to thereby flatten the same in cross section and spread the end portion to an extent greater than the cross sectional diameter of the tubular memher, and welding said sheared end edge member of the tubular portion to a plate.

4. A structural unit of the class described comprising spaced angle bars and tubular members having their extreme end edges welded to adja cent extreme edges of sides of said angle bars, said tubular members being sheared at their ends to flatten the same in cross section and to bevel the end edges transversely to the planes of the flattened portions, the peaks of the beveled end edges of said tubular members abutting adjacent extreme edges of sides of said angle bars, to provide a space between portions of the beveled edges of the tubular members and adjacent extreme edges of sides of said angle bars for receiving weld material for joining the same together.

5. A structural unit of the class described com prising spaced angle bars and tubular members having their extreme end edges welded to adjacent extreme edges of sides of said angle bars, said angle members having their said extreme edges beveled, said tubular members being sheared at their ends to flatten the same in cross section and to bevel the end edges transversely to the planes of the flattened portions, the peaks of the beveled end edges of said tubular members abutting the peaks of adjacent extreme edges of sides of said angle bars, to provide a space between portions of the beveled edges of the tubular members and adjacent extreme edges of sides of said angle bars for receiving weld material for joining the same together.

6. The process of making a beam, girder, boom, or the like which comprises shearing a tubular member at an end thereof to thereby flatten the same in cross section and beveling the end edge transversely to the plane of the flattened portion, placing the peak of said beveled end edge in abutment with a plate, and filling the intervening space between said end edge and said plate with weld material.

7. The process of making a beam, girder, boom, or the like which comprises shearing a tubular member at an end thereof to thereby flatten the same in cross section and beveling the end edge transversely to the plane of the flattened portion, beveling the adjacent edge of a plate to be connected thereto, placing the peak of the plate edge bevel in contact with the peak of the edge bevel of said member, and fllling the intervening space between said edge of said tube and the edge of said plate with weld material.

8. A structural unit as .claimed in claim 7 wherein the ends of the tubular members are sheared so that the peak lines of the end edges of each tubular member are parallel and disposed at an angle to the longitudinal axis thereof.

9. A structural unit of the class described, comprising spaced angle bars and tubular members whose normal end diameters are larger than the thickness of the edges of the legs of the angle bars to be connected thereto, said tubular members being flattened at the extreme end edge portions to a thickness substantially equal to that of the edges of the angle bar legs, and butt welding joints connecting said edges of the angle bars and the end portions of the tubular members.

HOLGER L. MITCHELL. 

